I think it depends on the state. We're still in FL, but thinking about heading back north in a month or so. At our MD house we're about 3 miles from the DE line, and from what I understand DE is stopping cars with out of state plates (like our FL plates) and fining them and threatening jail time. I think the exception is people who can prove they've quarantined for 14 days. And how can you possibly prove that?
The last news I heard, the DE state police were stopping out-of-staters that were coming to shop and sending them back to their states. At that time, those people were supposed to be sheltering in their own states (PA & NJ drivers were interviewed). They were not stopping cars traveling through DE to other destinations on interstates. If you were staying in DE, you had to quarantine yourself for 14 days. This was last week or the week before that I saw on the news. Since you live in Maryland why would Delaware be a problem for you.